i see what your problem is. first off don't copy and paste it doesn't work as it was designed as a generic example and not runnable. ok in your radvd config change the prefix to your networks prefix. you'll find that on your tunnel details page. also in the startup config note these 2 lines
MY_TUNNEL_ADDR="(Client IPv6 address from my tunnel with /64 omitted)" # change me
MY_ROUTED_ADDR="(Routed /64 value from my tunnel with /64 omitted)" # change me
for the MY_TUNNEL_ADDR you change in between the quotes to what your tunnel details page says for your client IPv6 address. and as for the MY_ROUTED_ADDR change in between the quotes to a new IP inside your routed IPv6 block.
just for an example lets say your block is 2001:470:15c5:2c54::/64 you pick a random IP to be the one for MY_ROUTED_ADDR and lets say you pick 2001:470:15c5:2c54::4 your new line will be:
and thats all you need to get that part running